The position or posture of a patient is a factor in various diseases and disorders, including those of the cardiac and/or respiratory systems. Certain disease processes may be exacerbated when the patient assumes particular postures. For example, obstructive sleep apnea episodes may begin or increase in frequency or severity when the patient lies down. In another example, congestive heart failure (CHF) patients frequently sleep with their torso tilted upward to reduce pulmonary congestion. Patient posture information may be used to enhance diagnosis of these and other diseases and disorders.
Posture sensing may also be used to enhance therapy delivery, such as cardiac pacing therapy. For example, changes in body posture can cause sudden decrease in blood pressure. For some patients, particularly the elderly and/or people taking certain medications, inadequate neural control of blood pressure may result in syncope upon rising from a sitting position or other sudden posture changes. Posture sensing may be used to improve cardiac pacing therapy during and after posture changes to promote physiologic pacing.
The present invention describes posture detection methods and systems including processes for calibrating and using posture detectors and offers various advantages over the prior art.